ke cew



a beating engine. I the best sizing results are obtained from the JUDSON A. DE CEW, 0F MONTREAL, QUEBEC, CANADA.

PROCESS OF TREATING PAPER-SIZE.

No Drawing.

Province of Quebec and Dominion of Canada, having invented certain new and useful Improvements in Processes of Treating Paper-Size, of which the following is a full, clear, and exact description.

This invention relates to the treatment of paper stock in beaters or mixers, and particularly to a process for increasing the eliiciency of sizing results under conditions Where chemical impurities and the like tend to injuriously affect the sizing results.

I have discovered by a great number of experiments that there is a certain chemical balance in rosin sizing reactions taking place in thewater surrounding the paper stock in Where rosin size is used,

use of acid resinates of soda, which are created by dissolving rosin in rosin soap and diluting this without decomposition, so that the unsaponified rosin is not free in a physical sense but is still in chemical equilibrium in the soap solution and can re-act in solution with other chemical salts.

A particular application of the present invention is in the carrying out of sizing reactions in the presence of hard water or other chemical impurities, such as calcium chlorids. Under such conditions, a large proportion of the acid resinate of soda will be precipitated by the earth salts in the form of calcium or magnesium resinates, which have very slight sizing value because these precipitates are not colloidal in character and are dehydrated very readily in the drying process. The main purpose of the process involved in this invention is to prevent this reaction taking place between the earth salts in the water and the resinate so- 'lution added to the paper stock for the pur Specification of Letters Patent.

I have determinedthis Patented Sept. 30, 1919.

- Application filed April 15, 1918. Serial 1 lo. 228,683.

ratio approximately both by laboratory test and by use in paper mill practice, and find that the amount of caustic soda or equivalent alkali necessary to add to hard water to prevent the formation of insoluble resinates With ordinary paper mill size is approximately one or two pounds of alkali as NaOH to twenty thousand pounds of water. The exact amount required of course depends on the hardness of the water, but it varies in practice from about one pound of alkali as a minimum to about four pounds as a maximum requirement.

This process may be carried out by using still more alkali but any increase over four pounds of NaOH to twenty thousand pounds of water begins to produce less efiicient sizing results, owing to the saponifying effect of the alkali upon the free rosin acids,

so that the commercial limits of obtaining the proper balance of reactions are approximately within the amounts specified. A partial result of this invention is shown in my U. S. patent application, Serial Number 17 2,- 035, filed May 31, 1917, in which sizing solutions are made containing both free rosin acids and -free alkali. Neither the purpose nor the results are, however, entirely fulfilled by the method described in said application, as there is an advantage in produc ing the alkalinity in the hard water of the beating engine before the size is added, thereby obtaining a much greater dilution before the free rosin acids and the free alkali come into contact.

In carrying out my process, I add to the water in which the paper stock is mixed in the beating engine approximately 1 lb. of alkali, calculated as NaOH. to 20,000 lbs. of water. This produces a faint alkalinity in the water, which can be recognized by means ofphenolphthalein or other indicators. Although this amount of alkali is insufiicient to effect saponification in the beater with the rosin acids of the sizing solution, yet the concentration of sodium if the calcium and magnesium salts were not present. As a. consequence the waterproofing qualities of the paper are not altered and more uniform sizing results are obtained. i

This process is of very great value because at the present time there are many paper making districts in which it is very difficult to obtain satisfactorysizing results, owing to the use of hard water in the paper mills. Moreover, it is a common practice to make white papers from paper stock con taining residues of bleaching solutions, such as calcium chlorid, and without any special treatment such as above described the Water resistance of the paper product will vary with the amount of these residues present and the injury which they do to the sizing material. The alkali which I prefer to use in this treatment is either sodium silicate, sodium aluminate or caustic soda. The alkalis of potash and ammonia can also be used but are more expensive and do not produce any better results. Alkaline carbonates can also be used but the caustic alkalis appear from experiments to be more effective for the purpose required.

Havingthus described my invention, what I claim is 1. A method of incorporating rosin size into paper stock in heaters or mixers without having it coagulated by earth salts which may exist in solution, which consists in adding a sufficient quantity of alkali so that the concentration of the basic ions will prevent the formation of earth resinates, then adding a resin size and finally precipitating with aluminum sulfate.

2. A method of reducing the solubility of calcium salts in the water surrounding the .paper stock in the beating engine, which consists in rendering this water slightly alkaline with soluble alkalis before adding thesizing solutions, then adding a resin size and finally precipitating with aluminum sulfate.

' 3. A method of inhibiting the effect of hard water in the beating engine, which consists in rendering the water which surrounds the paper stock slightly alkaline by means of a soluble alkali such as soda, potash or ammonia, then adding the rosin size, and finally precipitating same with sulfate of alumina.

4:. A method of sizing paper in a beating engine, which consists in adding approximately one pound of soluble alkali to twenty thousand pounds of water, whereby any dissolved calcium or magnesium salts' present in the water Will not react with sodium resinate, then adding a resin size and finally precipitating it with aluminum sulfate.

5. A method of treating water in which paper stock is mixed or beaten in a beating engine, which consists in adding suificient water soluble alkali, such as caustic-soda, so that the concentration of sodium ions will retard or prevent chemical precipitation between dissolved earth salts and so1uble resinates.

6. A method of treating water in which paper stock is mixed in the beating engine with approximately one pound of soluble alkali, such as soda, potash or ammonia, 'to twenty thousand pounds of Water before the sizing solutions are added.

In witness whereof, I have hereunto set my hand.

' JUDSON A. DE CEW. 

